Elias m



(No Model.)

E. M. GREENE.

PEOTEGTOE EOE TELEGRAPH AND TELEPHONE INSTRUMENTS. No. 297,385. Patented AprQZZ, 1884.

M l 1 l M1 I A 1K Z: 5

3 10 a, 01 p11 4 T 1 T G INVENTOR a; was Mme,

UNTT D STATES PATENT @ETTCE.

ELIAS M. GREENE, OE NEVV YORK, N. Y.

PROTECTOR FOR TELEGRAPH AND TELEPHONE ENSTRUMENTS.

SPECIFICATION forming part of Letters Patent No. 297,385, dated April 22, 1884.-

Application filed August 4, 1883.

(No model.)

in the county and State of New York, have invented certain new and useful Improvements in Protectors for Telegraph and Telephone Instruments, of which the following is a specification.

The object of my invention is to provide means for protecting telephones and telegraphic instruments from the injurious action of electric currents of greater intensity or volume than those normally traversing the circuits in which such instruments are included. It frequently occurs that the conductors of telegraph or telephone systems become entangled with neighboring electric-light conductors, and thus become media for conveying currents of abnormal intensity. Likewise also, during atmospheric electrical disturbances the conductors are often subjected to dangerous accumulations of electricity. The electro-magnets of the various working-instruments employed in telegraph and telephone systems are neither designed nor adapted to be traversed by such intense currents, the insulated conductors composing their coils not being of sufficient thickness and conductivity to permit the transmission thereof without injury. Vhen such currents pass through them,the wires become heated,thereby burning the insulated covering, and are even frequently fused, thus efiectually destroying the instruments. Various devices have been proposed for interrupting the normal circuit upon one side or the other of the instrument, and substituting therefor a connection with the earth or with the conductor upon the other side of the instrument, thus shunting the same out of the main circuit. Such devices are ineffective for the reason that the instrument is still in electrical connection with the highly-charged conductor, and will to a greater or less degree partake of its electrical charge.

My invention consists in organizing a device which will automatically interrupt the normal circuit uponboth sides of the instrument which is to be protected, and at the same time connect the extremities of the interrupted conductor with each other and with the earth independently of the instrument. For this purpose I make use of two electro-magnets, which, respectively, are normally included in the mainline circuit upon opposite sides of the instrument to be protected. Each of these electromagnets is provided with an ar1nature,through which one of the conductors leading from the coils of the respective electro-magnets is normally connected. Each armature normally rests against aninsulated back contact-stop, and these stops are united with each other through a conductor, in which is included the instrument to be protected. The armatures are respectively further provided with front contact-stops which are in electrical connection with each other, and also through a conductor of comparatively low resistance with the earth. Each armature is normally held away from its electro-magnet and against its back contact-stop by means of a retractile spring which is properly adjusted to prevent the armature from responding to currents not exceeding the normal strength. WVhen, however, an abnormal current traverses the main-line conductor and the two electro-magnets, the armatures will immediately respond to the increased magnetization of the cores, and by resting against their front contact-stops will act to both interrupt the circuit through the protected instrument and to place the two sections of the main line in electrical connection with each other, as well as with the earth, thus completely detaching the instrument from the circuit. When the abnormal current ceases, the armatures will, by the action of the retractile springs, resume their normal positions, thereby re-establishing the normal connections of the circuit, as at first.

In the accompanying drawings, which illustrate my invention as applied to a telephonecircuit, Figure l is a front elevation of an instrument embodying the same, showing in diagram the circuit-connections; and Fig. 2 is a plan of the said instrument.

Referring to the drawings,M and M, resp ectively, represent two confronting electro-magnets included in the main-line conductor L L of a telephone system. The terminals of the conductors L and L are respectively connected with the binding-posts l0 and 11, andthrough wires 13 and 14: with the outer terminals of the coils of the electro-magnets M and M, rcspectively. The electro-magnets M M are respectively provided with armatures a a and armature-levers m m. The armaturelevers are each provided with two contact-springs, b c and b c. The contactsprings b b, mounted upon the rear of the armatures, normally rest against two insulated contact-points, c and c,

which are supported in brackets of insulating material attached to a T-shaped metallic support, F, which is fixed upon the base A of the instrument between the confronting poles of the electro-magnets M and M. The support F also carries two adjustable front contactstops, f and f, for the armatures m and m. These stops are electrically connected with each other through the support, and also with the binding-post 5. The insulated contact-stops c and c are electrically connected through conductors l and 2, respectively, with two binding-posts, Sand 4. The telephone or other electrical instrumentT is included in the-conductors 6 and 7 between the binding-posts 3 and 4. Suitable adjustable retractile springs g and g respectively, extend from the armatures m and m to adjusting-screws h and h, carried in the standard of the support F. These springs are so adjusted that the armatures will be held away from the poles of their respective electro-magnets so long as currents of normal strength are transmitted through the main line. The pres ence of abnormal currents of sufficient intensity to injure the comparatively thin wires of the telephone or other instrument T, will cause the armatures to be drawn forward, and the contact-springs c and c to respectively rest. against their front contactstops, fandf,thereby completing a direct electrical connection between the inner terminals of the coils M and M. An earth-connection also will be completed at the same time through the bindingpost 5 and a conductor, 8, leading from the binding-post 5 to the earth at G. The conductor 8, as well as the conductors constituting the coils of the electro-magnets M M,should be of sufficient size and conductivity to permit the passage of abnormal currents of as great intensity as are liable in any case to be transmitted upon the main line without becoming fused or overheated. Upon the cessation of a current of sufficient strength to cause the armatures to approach their respective electro -magnets, they will be withdrawn and caused to assume their normal positions, as indicated in the are, thereby re-establishing the original connections through the telephone or other instrument.

I prefer to form the electric connection described through the armatures m and m by means of flexible springs, such as shown at b b and c c, for the purpose of obtaining more re liable contacts than may be secured by rigid contact-points.

For the purpose of furnishing additional protection to the instrument T against instantaneous currents of very high potential, such as are liable to be transmitted through the main line during severe thunder-storms, I. provide two lightning-guards of metal, 0 and 0, respectively, extending from the binding-posts 1 and 2 into proximity to the binding-post The guards 0 and 0' each consist of a metallic pin having at one end a screw-thread turning in a threaded aperture formed in its supporting binding-post, by means of which they may be adjusted to a greater or less distance from the binding-post 5. At the outer end of each pin is a flat head having a milled or corrugated surface. The faces of the binding-post 5, into close proximity to which these heads project, are flattened to correspond with the surface of the head. Any current of very high potential which might through the failure of the operation of the OlQOlilO lIljJQllGbS or for other reasons traverse the instrument T, will partially or wholly escape to the earth by jumping the narrow space separating the points 0 and 0 from the binding-post5in a manner well understood.

I claim as my invention 1. The combination, substantially as here inbefore set forth, with a main line and a telephone or telegraph instrument, of two electromagnets included in said main line, their armatures and armature-levers, two insulated rear contact-stops through which the circuitconnections with said telephone are normally completed, two front contact-stops in electrical connection with each other and'with the earth, and means, substantially such as described,whereby the circuit through said telephone will be interrupted at two independent points upon opposite sides of the same and the circuit of said main line completed inde pendently thereof, when said main line is traversed by currents of abnormal strength.

2. The combination, substantially as hereinbefore set forth, with a telephone or other electrical instrument, a main line in the circuit of which it is normally included, and means, substantially such as described, for interrupting the connections of said telephone upon each side thereof whenever a current of abnormal intensity traverses the main line, and substituting therefor electrical connections with the earth, of alightning-guard consisting of two adjustable milled surfaces extending from points in the conductor upon opposite sides of said telephone into close proximity with the conductor united with the earth.

3. The combination, substantially as here inbefore set forth, of two electromagnets, their armatures andarmature-levers, two contact-springs carried upon each of said levers, two insulated back contact stops, against which one of the contact-springs upon each of said levers normally rests, a telephone or telegraphic instrument included in a conductor uniting these two contact-stops, and In testimony whereof I have hereunto subtwo front contact-stops against which the rescribed my name this 2d day of August, A. D. maining springs upon said levers are caused 1883.

to impinge when said electro-magnets are trav- ELIAS M. GREENE. 5 ersed by currents of abnormal strength,which Witnesses:

front contact-stops are in electrical connection DANIEL W. EDGEcoMB,

with the earth. CHARLES A. TERRY. 

